Drilling in South America: A Wellbore Stability Approach for Complex Geologic Conditions

Willson, S.M.; Zoback, Mark D.; Moos, Daniel

doi:10.2118/53940-ms

Cited by 73 publications

(26 citation statements)

References 23 publications

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“…In anisotropic rocks bedding plane slip may have a significant effect on borehole and casing stability (Addis et al 1993;Dusseault et al 2001;Gazaniol et al 1995;Økland and Cook 1998;Russell et al 2003;Skelton et al 1995;Willson et al 1999) and has been estimated previously (e.g., Daemen 1983; Gallant et al 2007;Lee et al 2012;Vernik and Zoback 1990). However, the considerable effect of elastic anisotropy has been ignored so far in these analyses.…”

Section: Introductionmentioning

confidence: 91%

Influence of Bedding Angle on Borehole Stability: A Laboratory Investigation of Transverse Isotropic Oil Shale

et al. 2014

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The stability of wells drilled into bedded formations, e.g., shales, depends on the orientation between the bedding and the borehole axis. If the borehole is drilled sub-parallel to bedding, the risk of borehole instabilities increases significantly. In this study, we examined the formation of stress-induced borehole breakouts in Posidonia shale by performing a series of thick-walled hollow cylinder experiments with varying orientations of the bedding plane with respect to the borehole axis. The thickwalled hollow cylinders (40 mm in diameter and 80 mm in length containing an 8 mm diameter borehole) were loaded isostatically until formation of breakouts. The onset of borehole breakout development was determined by means of acoustic emission activity, strain measurements, ultrasonic velocities and amplitudes. The critical pressure for breakout initiation decreased from 151 MPa by approximately 65 % as the bedding plane inclination changed from normal to parallel to the borehole axis. The finely bedded structure in the shale resulted in an anisotropy in elasticity and strength from which the variation in strength dominated the integrity of the thick-walled hollow cylinders.

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Section: Introductionmentioning

confidence: 91%

Influence of Bedding Angle on Borehole Stability: A Laboratory Investigation of Transverse Isotropic Oil Shale

et al. 2014

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“…4. In addition, the anisotropy of shale strength has also been tested by a large number of researchers (Jaeger, 1960;Chenevert and Gatlin, 1965;Pinto, 1970;Jaeger, 1971;Vernik and Nur, 1992;Aoki et al, 1993;Ong, 1994;Vernik and Liu, 1997;Niandou et al, 1997;Willson et al, 1999Willson et al, , 2007Pei, 2008;Jaeger and Cook, 2009;Sondergeld and Rai, 2011;Kanitpanyacharoen et al, 2011;Wang et al, 2012;Li et al, Fig. 3.…”

Section: The Anisotropic Strength Of Shale Rockmentioning

confidence: 99%

A wellbore stability analysis model with chemical-mechanical coupling for shale gas reservoirs

Chen

2015

Journal of Natural Gas Science and Engineering

102

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“…Willson et al 1999), to completion engineering, where for example perforating and sand production are influenced by geomechanical parameters (e.g. Wiprut & Zoback 2000).…”

Section: Depicting Geological Uncertainty In 3d Modelsmentioning

confidence: 99%

Improved Drilling Performance through Integration of Seismic, Geological and Drilling Data

Stewart

Holt

2004

Memoirs

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Unexpected incidents leading to lost time when the rig is on location cause unplanned cost to the hydrocarbon industry of over one billion dollars annually. Processing and interpretation of 3D seismic data usually focuses on reservoir levels. But from a drillers perspective, geological features of the overburden are often more significant than those at reservoir level, since over 90% of the well is typically spent drilling the overburden, coping with a wider variety of challenges than those associated with the reservoir itself. 3D seismic data defines overburden tectonostratigraphy, the framework of a geological model that can be used in well planning to reduce geological uncertainty, surprises and expense along the whole well track. Many technologies applied in reservoir modelling are equally valid in defining overburden features relevant to well planning. The overburden 3D volume can be populated with key parameters for well design, such as pore pressure and geomechanical attributes, though the complexity of the model will often be restricted by well cost and perception of drilling risk. The role of 3D seismic data in forming the tectonostratigraphic framework of multi-attribute, kilometre-scale Earth models, is illustrated here by a number of examples where model sophistication has been scaled to match project requirements. Overburden Earth models also provide a framework where several "academic" research themes, for instance 3D fault geometry, can be put into a commercial context. Construction of overburden models for well planning has also highlighted a number of future geological research areas that could have a significant impact on drilling performance. Some of these, such as hydraulic properties of fault systems, are highlighted here.No petroleum industry operating company has a global monopoly of best in class drilling performance ('best in class' is defined here as fewest days per depth drilling performance in a given fairway or trend). Gaps between performance of a specific well and best in class arise from the sum of non productive time events (unplanned time where no hole is being made) and 'train wrecks' (major events where drilling has to be abandoned and restarted). Many of these incidents occur in the overburden section between the mud line and top reservoir (Fig. 1)--a zone often neglected in terms of geological input to well planning. The annual cost to the industry of these incidents in offshore wells alone is in the order of one and a half billion dollars (Table 1). This cost estimate discounts the effects of weather and time lost to equipment failure. A further element of the gap between performance of a given well and best in class can be attributed to operational inefficiency (Bond et al. 1996), which has not been factorized in the numbers shown in Table 1. 3D seismic data inherently provides the fundamental framework of a 3D model that spans the entire overburden. This represents a broader use of 3D seismic data than more usual reservoir-specific application, We term the kilometre-scale ...

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Drilling in South America: A Wellbore Stability Approach for Complex Geologic Conditions

Cited by 73 publications

References 23 publications

Influence of Bedding Angle on Borehole Stability: A Laboratory Investigation of Transverse Isotropic Oil Shale

Influence of Bedding Angle on Borehole Stability: A Laboratory Investigation of Transverse Isotropic Oil Shale

A wellbore stability analysis model with chemical-mechanical coupling for shale gas reservoirs

Improved Drilling Performance through Integration of Seismic, Geological and Drilling Data

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